Abstract

We have investigated the energetics of the N vacancy formation in by ab initio calculations. We identify N sites (Wyckoff notation) in as the most probable vacancy sites based on the energetics of vacancy formation. Furthermore, does not exhibit any states at the Fermi level. Introducing N vacancies causes states to appear at the Fermi level, which may enable electron transport. Recently measured conductivity data [Finkel et al., Phys. Rev. B67, 235108 (2003)] for can be understood based on our calculations.

Received 13 July 2004Accepted 26 November 2004Published online 12 January 2005

Acknowledgments:

The authors acknowledge financial support from the Swedish Research Council. J.M.S. also acknowledges the Alexander von Humboldt Foundation, the German Federal Ministry of Education and Research and the Program for Investment in the Future. All calculations were carried out at NSC, Linköping, Sweden, and made possible through Swedish National Allocations Committee.